The present invention relates as indicated to an impact absorbing base, and relates more particularly to a base which can be used for playing baseball or softball and which greatly minimizes injuries to players contacting, particularly sliding into, the base.
Bases must possess certain characteristics, one of which is that the base must not be shiftable when touched, stepped upon or slid into. That is, the base must not be allowed to laterally shift. Bags are frequently retained in place by long spikes which are separate members and adapted to receive a strap attached to the bottom of the bag for securing the base to the spike which is driven into the ground. A second form of base and one which is used at the major and minor league levels comprises a base formed with a downwardly extending post on the undersurface of the base, with the post extending into a complementary shaped retaining sleeve embedded in the soil. The connection is typically non-rotating, with the post and retaining sleeve assembly thus precluding the base from either rotating or shifting laterally.
Break away bases are also known. This type of base breaks away from its mounting when impact forces above a certain level are encountered. One of these break away bases is shown in U.S. Pat. No. 4,398,715, issued to Hall. The patented arrangement comprises a base top which is detachably secured to a ground plate or equivalent holding device. The momentum of a sliding player shears or breaks away the detachable upper portion of the base from the fixed ground plate. This type of base has the disadvantage that the base must be retained in place on the fixed ground plate unless and until certain energy levels are reached, thereby requiring rather elaborate interconnecting means between the base and the fixed ground plate. There are numerous anchoring points, all of which must be secured in order to re-attach the base to the plate after the base has been broken away. Moreover, when impact forces cause the base to break away from its associated mounting, the base frequently is separated from the sliding player, thereby making rulings of safe and out relatively difficult. Further, if the base is detached from its mounting when not in use, for example, to prevent theft, the anchoring portion of the assembly is exposed to damage from weather or vandalism when the playing field is not in use.
A further solution is proposed in U.S. Pat. No. 5,000,447, issued to the present inventor. While the base disclosed in the '447 patent has performed very well and has been commercially successful, its size and mounting do present certain difficulties. The base was primarily designed for use on playing fields particularly adapted for relatively advanced players. The base is therefore comparable to bases then and still being used at the high school, college, minor and major league levels. In addition, the base was mounted by means of a specially configured post adapted to extend into an embedded retaining sleeve for anchoring the base in such sleeve. This requires relatively permanent base installations thereby increasing both the purchasing and installation costs for a set of bases of the type disclosed in the patent. This has proven to be a particular problem for operators of fields for very young players, where budget limitations normally do not justify the purchase of the more advanced base assemblies disclosed in the '447 patent, despite the concern of virtually everyone for the safety of young players.
From the above discussion it will be understood that there are number of design parameters that must be considered in the design of an impact absorbing base. The base must be rigid enough to be stepped on without deforming, and at the same time resilient enough to deform and absorb the impact of a player sliding into it. The impact absorption characteristic of the base must be such that it adequately absorbs impact forces of younger, lighter weight players, as well as older, heavier players, from the substantial impact forces resulting from sliding into the base. Moreover, the base and anchoring arrangement must be such that it meets the above criteria while at the same time being affordable to the widest possible range of field environments, from the very youngest players to the most experienced professional players.